Release system for radiographic exposures



p 1963 k. K. BERGLUND ETAL 3,103,590

RELEASE SYSTEM FOR RADIOGRAPHIC EXPOSURES F iled June 28, 1961 2 Sheets-Sheet 1 f Y 4 swam-new GENERATOR 1 I j: i /104, v AMPLIHER RECTIFIER POWER SUPPLY FI G 1 AMPLIFIER Kurt K. Berglund Axel 0. Jacobsspn,

Gustav A. Magru INVENTORS 1 1 K. K. BERGLUND ETAL 3,103,590

RELEASE SYSTEM FOR RADIOGRAPHIC EXPOSURES Filed June 28, 1961 2 Sheets-Sheet 2- Auooe ROTATOR FILAMENT POWER 22 1 SUPPLY POWER 24b, 5 {7 J I 1 EXPOSURE Tl M ER I L 15 FIG. 5

Fnzsr sscouo AMPLIFIER AMPLIFIER 5m 6 E STAGE I 10 f 'kzcrmsa RECTIFIER a g 'ExPasuRE 18 TIN ER k 11 1, Kurt A. Berqlund. Axel O. Jacobsson POWER Gustav A. Magm JNVENTORS Fr 6. 4

United States Patent 3,103,590 RELEASE SYSTEM FOR RADIOGRAPHIC EXPOSURE Kurt K. Bel-gland, Solna, Axel O. Jacobsson, Framuasbacka'n, and Gustav A. Magui, Lidingo, Sweden, assignors to Jarnhs Elektriska Aktiebolag, Solua, Sweden, a corporation of Sweden Filed June 28, 1961, Ser. No. 120,393 Claims priority, application Sweden July 9, 1960 7 11 Claims. (Cl. 250-93) By using a remote control in this way the operator of the X-ray apparatus is enabled to stay at such a distance from the apparatus that the danger of exposure to radiation will be substantially eliminated. It is obvious, however, that there is no absolute guarantee-that the operatorof the apparatus will always observe the precaution of staying at a safe distance [from the X-ray apparatus when radio graphic exposures are released.

The present invention relates to a release system for an X-ray apparatus, in which a stray-field generator for producing an extrinsic magnetic, electric or electromagnetic field is arranged to cooperate with receiving means associatedwith the X-ray apparatus so as to cause an exposure at the X-ray apparatus to be released by the field thus excited.

The principal characterizing feature of the invention resides in that the receiving device is arranged and interconnected with the X-ray apparatus in such a way-thata release of hhe X-ray apparatus is enabled only when the stray-field generator, althoughsituat-ed withinits active range, is more remote trom the X-ray apparatus than a predetermined distance.

Further objects, advantages and features of the present invention will be apparent from the following description, taken with the accompanying drawings, in which:

FIG. 1 is va circuit diagram of a release system to be described as one illustrative embodiment of the present invention; r I

FIG. 2 is a fragmentary circuit diagram showing a modified release system; and I FlGS. 3 and 4 are fragmentary circuit diagrams illustrating further modifications.

In describing the embodiments of the present invention, it will be assumed that (the stray-field generator 4 emits electromagnetic waves. The circuit or the stray-field generator 4-, serving lfOI emitting such electromagnetic waves, is not illustrated but may include an oscillator comprising a transistor and a pair of windings connected in pushpull relation to each other andmounted on a termite rod core. The transistor together with the windings and an adequate source of electric current are disposed in a case which, in addition, is provided with an externally operable switch-in device for the oscillator. Such switch-in "device may be in the form of a push-button-switch 4a adapted when depressed to apply the source of current to the transistor, thereby starting'the stray-field generator into operation and creating oscillations so as to build up an extrinsic electromagnetic field.

The X-ray apparatus is associated with a receiving device 5 which is operable by the field produced by the stray-field generator. In the embodiment shown in FIG. I the receiving device comprises a ferrite rod 7 having a winding Sadapted to be tuned to the frequency of the stray-field generator by means of a capacitor 9. The

voltage induced across the winding 8. is applied to an amplifier it; and then to a rectifier 18a, in which a rectifienergized Whenever the output voltage nfrom'the amplifier when the stray-field generator is operated while it is situated within a range such that the generator is able to create a suificient signal level at the receiving device. The relay 11a, when energized, closes a pair of contacts 12, establishing a circuit from the power supply through the normally-closed contacts 120, the contacts 12, a device 13 comprising an exposure timer, and back to the power supply. Connected to the exposure timer is a contactor ldw hich then functions to close the circuit through the primary winding 14 of the transformer of the X-ray apparatus, whereby the X-ray tube 17 will have hightcnsion electric power applied to it from the secondary winding 15 for the duration as determined by the exposure timer 13, after which the contactor 16 acts to cut oil the power supply.v

The principal characterizing [feature of this embodiment resides in the second nelay 11b, which includes the normally-closed contacts 12a as mentioned hereinbefore, This second relay 11b has a sensitivity which is much lower than that ot the first relay 11a and therefore will not be energized sufiiciently from the amplifier to be able thus no X-ray exposure can take place any longer. Thus, the arrangement shown will automatically rfunction in such a manner that, at too short distances of the strayfield generator them the receiving device and X-ray apparatus, the latter will be unable to perform as exposure. This Will afford an automatic protection against the danger of the operator being subjected to excessive doses of radiation. The exposure (timer 13 may be arranged so as to be insensitive to brief impulses so that the timer will not be operated if the relay 11a operates slightly [faster than the relay lib. A variable resistor 18 is connected in series with the relay 11b to regulate the current through such relay.

A further embodiment of the invention is shown in FIG. '2, this figure, however, including only the components of particular interest, whereas the remaining structure forming part of a complete system have been omitted in order to render thecircuit diagram more'perspicuous.

which is connected as a degenerative current feedback phase inverter having a resistor R, in its collector circuit and a variable resistor R in its emitter circuit. By means of the last-mentioned resistor R the gain of the amplifier is adjustable.

The two transistors T and T are connected in circuit 7 with each other in such a Way that current flows from the negative terminal of the current source to the collector of transistor T the emitter circuit of T 3 being extended through a relay 11c and thence to the collector of transistor T and from the emitter of this transistor T .to the positive terminal of the current source. The base of transistor T is supplied from the previously mentioned point A, and the base of transistor T is supplied from the point 13, ie; from the collector of transistor T 'lhe mode or" operation of the arrangement is as follows: In order to cause relay to operate and close its tube is equipped with a rotaryanode. will remain also atfter the stray-field generator has subbefore.

the exposure tinier 13, for example, it is necessary for both transistors T and T to be conducting. When a voltage is present across the coil L, a negative voltage will develop at point A and this negative voltage will become higher, the higher the voltage becomes across coil L, ie the shorter the distance of the receiver from the stray-field generator.

At a certain negative voltage at point A, the transistor T will commence to conduct, and the higher the negative voltage at point A, the higher will be the current passed by the transistor. The voltage at point B which controls the current-conducting capacity of transistor T is dependent also on the negative potential at point A, the potential at point B commencing to decrease as the transistor T begins to conduct. A voltage reduction at point B will involve current reduction through transistor T Owing to the connection of transistor T as a degen- V erative feedback current phase inverter, and rowing to T field generator (from the receiver is smaller, the highernegative potential then appearing at point A will be suflicient to cause transistor T to conduct, but will be insufiicient to bias' transistor T to cut-off. Thus relay 110 will be energized and'will operate to energize the exposure timer 13 in the manner already described.

' Upon still further reducing the distance of the stray field generator from the receiver, the negative potential at point A will be still higher, and, as described hereinbetore, the transistor T will remain in its conducting state whereas, at a certain magnitude of the negative potential at point A, thecurrent flow through transistor will be cut-off or reduced to a value which is insufficient to energize the relay 11c. By adjustment of the resistor R this cut-ofi potential at point A may be adjusted thus resulting simultaneously in an adjustment of the minimum distance which must be present between the stray-field generator and the receiver in order that operation to cause release will be possible.

According to a further development of the invention,

" the receiving device may be provided with means causing a step-by-step release of the exposure procedure. Upona first depression of the push-button switch of the strayfield generator, the X-ray apparatus will be conditioned for release by switching on the filament supply for the X-ray tube and starting the anode rotating device, if the This connection sequently been rendered inoperative. Upon a second depression to switch on the stray-field generator the exposure will then be released in the manner described herein In both instances the arrangement is suitably so devised as to inhibit any switching-in or release, respectively, when the distance of the stray-field generator from the receiving device and X-ray apparatus is too short.

. Thus, in the arrangement of FIG. 3, the relay 110 of' FIG. 2 is rep-laced by a stepper 11d having a contact sector 22 which is movable successively into engagement with contacts 24 and 26. The contact 24 is connected to the filament power supply 28 and the anode rotator 30',

- so that they will be'energized in response. to the first depression of the push-button switch 4a on thestray-field generator 4. The contact 26 is connected to the exposure timer 13. Upon the second depression of the push-button switch 4a, the contact sector 22 is advanced so as to engage both of the contacts 24- and 26 so that the timer .13 will be triggered, while the filament power supply 28 and the anode rotator 30 remain enengized. The stepper 11d may be of the type which returns automatically to its home position.

The arrangement shown in the drawing comprising differently sensitive relays may, of course, be diiierent from 7 that shown, it being, for example, within the scope of the invention to connect relay 11b to a preceding stage of the amplifier 10 in which case it would be possible to utilize substantially equal current sensitivities for both'relays 11a nal level, while the relay 11b will be operated at a rela- Whenthe stray-field gen- 7 tively high input signal level. erator is too close to the X-ray machine, both relays will be operated. The operation of the relay 11b nullifies the effect of the operation of the relay lla so that the exposure timer 113 will not be actuated.

We claim:

1. A release system for an X-ray apparatus, comprising a selectively operable stray-field generator, release means for controlling the exposure of the X-ray apparatus, and

a receiver for receiving the signals from said stray-field generator, said receiver including first means operable in response to signals greater than a first level foractuatiug said release means, and second means operable in response to signals greater than a second level, substantially higher: than said first level, for nullifyin-g the effect of said first means and preventing the actuation of said releasemeans, so that the X-ray apparatus will not 'be released it the stray-field generator is brought within a predetermined distance from said receiver.

2. A release system according to claim 1, in which said first means comprises a first relay having normally open contacts, said second means'comprising a second relay having normally closed contacts, said second means being operable at a higher signal level from saidstray-field generator than said first relay, and a control circuit connected to said release means and connecting said normally open contacts and said normally closed contacts in series so that said release means will not be actuated when both of said relays are energized.

3. A release system according to claim 2, in which said receiver comprises an amplifier for operating said relays, said amplifier'having a plurality of amplifying stages, said first relay being connected to said amplifier after a larger devices having output circuits connected in series to said release means so that both of said electronic devices must 7 be conductive to actuate said release means, means for 5. A release system according 'to claim 4, in which said electronic amplifying devices comprise'transistors having their output circuits connected in series to said release means.

6. A release system according to claim 1, in which said receiver comprises first and second electronic devices having their output circuits connected in series to said release means, means for causing said first electronic device to conduct when the signals from said stray-field generator exceed said first level, and means for rendering said second electronic device nonconductive when the signals from said generator exceed said second level.

7. A release system according to claim 6, in which the means for rendering said second electronic device nonconductive comprises a degenerative phase inverter supplied with the same input signals as said first electronic device.

8. A release system according to claim 6, in which said electronic devices comprise transistors having their output circuits connected in series so that both transistors must be conductive to actuate said release means.

9. A release system according to claim 7, including means for adjusting the loss introduced by said degenerative phase inverter.

10. A release system according to claim 1, in which said release means comprises a stepping device for sequentially energizing the filament supply and the anode supply of the X-ray apparatus in response to successive intervals of operation of said stray-field generator.

1 1. A release system for operating an X-ray apparatus in response to stray fields developed by a selectively operable stray-field generator, said system comprising release means for controlling the exposure of the X-ray apparatus, and a receiver for receiving the signals from said strayfield generator, said receiver including first means operable in response to signals exceeding a first level for actuating said release means, and second means operable in response to signals exceeding a second level for nullifying the effect of said first means and preventing the actuation of said release means, said second level being substantially higher than said first level, said second level corresponding to the signal strength developed by the stray-field generator at the minimum safe distance from said X-ray apparatus so that the exposure of the X-ray apparatus will not be released if the stray-field generator is brought closer to the apparatus than the minimum safe distance.

References Cited in the file of this patent UNITED STATES PATENTS 2,203,811 Koch June 1'1, 1940 2,293,166 Olson Aug. 18, 1942. 2,928,002 Havstad Mar. 8, 1960 2,930,942 Levine et a1 Mar. 29, 1962 

1. A RELEASE SYSTEM FOR AN X-RAY APPARATUS, COMPRISING A SELECTIVELY OPERABLE STRAY-FIELD GENERATOR, RELEASE MEANS FOR CONTROLLING THE EXPOSURE OF THE X-RAY APPARATUS, AND A RECEIVER FOR RECEIVING THE SIGNALS FROM SAID STRAY-FIELD GENERATOR, SAID RECEIVER INCLUDING FIRST MEANS OPERABLE IN RESPONSE TO SIGNALS GREATER THAN A FIRST LEVEL FOR ACTUATING SAID RELEASE MEANS, AND SECOND MEANS OPERABLE IN RESPONSE 